Individuals as controllers of danger

Ergonomics has taught us that we should never expect to eliminate human error completely. Anyone who conscientiously logs all the errors they make will come up with several, if not tens, per hour. If your rate of typing errors is anything like mine, it can even run into hundreds per hour. Most errors have few consequences most are corrected on the spot. 

Such a model gives us a more dynamic picture of safety, which is particularly useful for systems such as aviation, which depends on good on-line dynamic control of risk. The older, more static models are adequate for more static safety provisions such as machinery guards. 

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